862 THE PHYSIOLOGY OF REPRODUCTION. 



seminal vesicles in white rats prevents successful fertilization of the 

 female, although the ability and desire to copulate is not interfered 

 with. Direct experiments show that the secretion of the prostate 

 gland maintains motility much more efficiently than a solution of 

 physiological saline. It seems certain that the secretions of the mu- 

 cous membrane of the uterus and Fallopian tubes exercise a similar 

 favorable influence. Kolliker and others have investigated the 

 action of many substances upon the motility of the spermatozoa, 

 such as acids, alkalies, salts of various kinds and in different con- 

 centrations, sugar, ethereal oils, etc. The union of spermatozoon 

 and ovum is believed to take place usually in the Fallopian tube, 

 and under normal conditions only one spermatozoon penetrates 

 into the egg. The remainder of the infinite number that may be 

 present eventually perish. The changes that take place during 

 the process of fertilization have already been described (p. 850). 

 Chemistry of the Spermatozoa. Much chemical work has 

 been done upon the composition of spermatozoa, particularly in 

 the fishes. The results have been most interesting from a chem- 

 ical standpoint, and biologically they are suggestive in that the 

 analytical work has been done upon the heads of the spermatozoa. 

 These heads consist entirely of nuclear material, and constitute 

 the substance which conveys the hereditary characteristics of the 

 father. Whatever progress may be made in the understanding 

 of the chemistry of this material is a step toward the solution of 

 the most difficult and mysterious side of reproduction, the power 

 of hereditary transmission. Miescher in investigations upon the 

 spermatozoa of salmon discovered that the heads are composed 

 essentially of an organic combination of phosphoric acid, since 

 designated as nucleic acid, united with a basic albuminous body, 

 protamin. This view has been confirmed and extended by later 

 observers, especially Kossel and his pupils.* The head of the 

 spermatozoon, the male pronucleus in fertilization, might be de- 

 fined, in the case of the fishes at least, as "a salt of an organic 

 base and an organic acid, a protamin-nucleic acid compound." 

 The term protamin is used now to designate a group of closely 

 related substances obtained from the spermatozoa of different 

 animals. The special protamin of each species is designated ac- 

 cording to the zoological name of that species; thus the protamin 

 of salmon is salmin, of hering (Clupea harengus) clupein, and so on. 

 The protamins are all strong bases; their aqueous solutions give 

 an intense alkaline reaction, and they unite readily with various 

 acids to form well-defined salts. They are albuminous bodies, 

 giving the biuret reaction readily even without the addition of 



* For literature and details of the chemistry of spermatozoa see Burian, 

 in " Ergebnisse der Physiologic," vol. iii, part i, 1904. 



